Non-fusion scoliosis expandable spinal rod

ABSTRACT

A growing rod for mounting between attachment mechanisms that are secured to anatomical structures of a patient having scoliosis. The growing rod includes a base rod having an attachment end, an extendable rod that is translatable relative to the base rod along a longitudinal axis and a housing enclosing at least a portion of the extendable rod therein. A magnet is rotatably mounted within the housing and is enclosed by a top magnet cover and a bottom magnet cover. The magnet includes a first pole and a second pole. A gear reduction mechanism is associated with the magnet and the extendable rod. The gear reduction mechanism reduces an output rotation to the extendable rod relative to an input rotation from the magnet.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/056,441 filed Oct. 17, 2013, entitled “Non-Fusion ScoliosisExpandable Spinal Rod,” which is a continuation of U.S. application Ser.No. 12/957,447, filed Dec. 1, 2010, entitled “Non-Fusion ScoliosisExpandable Spinal Rod,” now U.S. Pat. No. 8,568,457 which claimspriority to U.S. Patent Application No. 61/265,568, filed Dec. 1, 2009,entitled “Non-Fusion Scoliosis Expandable Spinal Rod,” the entiredisclosures of which [are incorporated herein by reference in theirentirety.

BACKGROUND OF THE DISCLOSURE

Scoliosis is a medical condition where an individual's spine curves offof its anatomical shape, typically in an “S” or “C” shape, and may alsobe rotated about a vertical axis or a longitudinal axis of the spine.Scoliosis can be a particularly painful and dangerous condition foryoung persons including infants, juveniles and adolescents, who are notfully grown. Young persons with scoliosis may be treated in variousmanners depending upon age, severity of the curve and the likelihood ofprogression of the condition. Conventional options for scoliosis includeobservation, bracing and surgery.

Surgery is typically indicated for juvenile scoliosis when there is ahigh likelihood of progression, the curve is causing significant painand/or the curve is impacting physiological functions, such asbreathing. Surgical intervention typically results in fusion of theimpacted portion of the spine, which is ideally delayed until thepatient is skeletally mature. However, certain severe cases of juvenilescoliosis require surgical intervention prior to skeletal maturity toprevent progression of the curve and/or to stabilize the spine. Multiplesurgeries in such cases are common to gradually correct the curvatureand/or modify the surgical construct to permit growth or to graduallymove the curved or twisted spine.

SUMMARY

The present disclosure relates generally to orthopedics. Morespecifically, the disclosure relates to a non-fusion scoliosis constructincluding a magnetically actuated growing rod that permits extension ofthe rod, growth of the construct and extension or correction of apatient's spine without significantly invasive surgical intervention.The device includes an actively expandable rod that is mounted to apatient's spine or ribs using hooks, screws and/or other fasteningmechanisms to be fixed to the posterior of the patient's spine or tonearly any other portion of the patient's spine that permits correctionof an undesirable spinal curvature. The system is preferablymagnetically activated from outside of the patient's body utilizing amagnetic field without further surgery for expansion. The system istypically indicated for adolescent idiopathic scoliosis, early onsetscoliosis and/or thoracic insufficiency syndrome, but is not so limitedand may be utilized to treat nearly any type of scoliosis or may beemployed in nearly any treatment where extension of a rod mounted withina patient is desirable, without the necessity for invasive surgicalintervention.

In accordance with some implementations, there is provided a growing rodfor mounting between attachment mechanisms that are secured toanatomical structures of a patient having scoliosis. The growing rod mayinclude a base rod having an attachment end and an extendable rod beingtranslatable relative to the base rod along a longitudinal axis. Ahousing may enclose at least a portion of the extendable rod and amagnet that is rotatably mounted within the housing. A gear reductionmechanism associated with the magnet and the extendable rod may beprovided that reduces an output rotation to the extendable rod incomparison to an input rotation from the magnet.

In accordance with some implementations, there is provided a growing rodthat may include a housing, a fixed rod that is attached to the housingat a first end of the housing, and an extendable rod that moves along alongitudinal axis of the growing rod and extending from a second end ofthe housing. A magnet mounted within the housing may be provided suchthat movement of the magnet caused by an external magnetic field isinput to a gear reduction mechanism. The gear reduction mechanism mayreduce the input movement to produce an output that is translated intolongitudinal movement of the extendable rod.

In accordance with some implementations, there is provided an expandablespinal growing rod that may include a first rod that is fixedly attachedto a housing at a first end of the housing and a second rod that extendsfrom a second end of the housing and that moves along a longitudinalaxis. A magnet may be provided within the housing that engages a gearmechanism. Input rotational movement of magnet may drive the gearmechanism, which is translated into longitudinal movement of the secondrod relative to the housing.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofseveral implementations of the device and methods of the presentapplication, will be better understood when read in conjunction with theappended drawings. For the purposes of illustrating the growing rod ornon-fusion scoliosis expandable spinal rod of the present application,there are shown in the drawings several implementations. It should beunderstood, however, that the application is not limited to the precisearrangements and instrumentalities shown. In the drawings:

FIG. 1 illustrates a top perspective view of a growing rod or non-fusionscoliosis expandable spinal rod in accordance with a firstimplementation of the present application;

FIG. 1A illustrates a posterior view of a spine with several of thegrowing rods of FIG. 1 mounted thereto;

FIGS. 2A-2C illustrate side elevational, front and rear elevational andtop plan views of the growing rod of FIG. 1;

FIGS. 3A-3B illustrates cross-sectional views of the growing rod of FIG.1, taken along lines A-A and B-B of FIGS. 2A and 2B, respectively;

FIGS. 4A-4C illustrate various cross-sectional and a rear elevationalview of the growing rod of FIG. 1;

FIGS. 5A-5B illustrate an exploded view and a magnified exploded view ofcomponents taken from within the circle Y of the growing rod of FIG. 4C,respectively;

FIGS. 6A-6D illustrate several views of magnetic activation of a magnetof the growing rod of FIG. 1;

FIGS. 7A-7D illustrate a top perspective view of a growing rod inaccordance with a second implementation of the present disclosure;

FIGS. 8A-8E illustrate several plan, elevational and cross-sectionalviews of the growing rod of FIGS. 7A-7D;

FIGS. 9A-9B illustrate an exploded view and a magnified exploded view ofcomponents of the growing rod of FIGS. 7A-7D, respectively;

FIGS. 10A-10C illustrate a top perspective view of a growing rod inaccordance with a third implementation of the present disclosure;

FIGS. 11A-11E illustrate several plan, elevational and cross-sectionalviews of the growing rod of FIGS. 10A-10C;

FIGS. 12A-12B illustrate an exploded and a magnified exploded view ofseveral components of the growing rod of FIGS. 10A-10C;

FIGS. 13A-13C illustrate a top perspective view of a growing rod inaccordance with a fourth implementation of the present disclosure;

FIGS. 14A-14E illustrate several plan, elevational and cross-sectionalviews of the growing rod of FIGS. 13A-13C;

FIGS. 15A-15B illustrate an exploded view and a magnified exploded viewof components of the growing rod of FIGS. 13A-13C, respectively;

FIGS. 16A-16C illustrate a top perspective view of a growing rod inaccordance with a fifth implementation of the present disclosure;

FIGS. 17A-17E illustrate several plan, elevational and cross-sectionalviews of the growing rod of FIGS. 16A-16C;

FIGS. 18A-18B illustrate an exploded view and a magnified exploded viewof several components taken from the growing rod of FIGS. 16A-16C,respectively;

FIG. 19 illustrates a top perspective view of a growing rod inaccordance with a sixth implementation of the present disclosure;

FIGS. 20A-20H illustrate several plan, elevational and cross-sectionalviews of the growing rod of FIG. 19;

FIGS. 21A-21D illustrate several operational steps of a mechanism of thegrowing rod of FIG. 19, shown in a forward bias position;

FIGS. 22A-22D illustrate several operational steps of a mechanism of thegrowing rod of FIG. 19, shown in a reverse bias position;

FIGS. 23A-23B illustrate an exploded view and a magnified exploded viewof several components of the growing rod of FIGS. 19 and 20A-20H,respectively;

FIGS. 24A-24E illustrate several views of a ratchet arm of the growingrod of FIGS. 19 and 20A-20H and related components;

FIG. 25 illustrates a top perspective view of a growing rod inaccordance with a seventh implementation of the present disclosure;

FIGS. 26A-26H illustrate several plan, elevational and cross-sectionalviews of the growing rod of FIG. 25;

FIGS. 27A-27B illustrate an exploded view and a magnified exploded viewof components the growing rod of FIG. 25, respectively;

FIG. 28 illustrates a top perspective view of a growing rod inaccordance with an eighth implementation of the present disclosure;

FIGS. 29A-29E illustrate elevational and cross-sectional views of thegrowing rod of FIG. 28;

FIGS. 30A-30B illustrate an exploded view and a magnified exploded viewof components of the growing rod of FIG. 28, respectively;

FIGS. 31A-31B illustrate magnified cross-sectional views of the growingrod of FIG. 28 taken from within circle Y of FIG. 29E and along line c-cof FIG. 29A, respectively;

FIG. 32 illustrates a top perspective view of a growing rod inaccordance with a ninth implementation of the present disclosure;

FIGS. 33A-33G illustrate top plan, elevational and cross-sectional viewsof the growing rod of FIG. 32;

FIGS. 34A-34B illustrate an exploded view and a magnified exploded viewof components of the growing rod of FIG. 32;

FIG. 35 illustrates a top perspective view of a growing rod inaccordance with a tenth implementation of the present application;

FIGS. 36A-36B illustrate an exploded view and a magnified exploded viewof components of the growing rod of FIG. 35, respectively;

FIGS. 37A-37G illustrate elevational, cross-sectional and magnifiedcross-sectional views of the growing rod of FIG. 35;

FIG. 38 illustrates a top perspective view of a growing rod inaccordance with an eleventh implementation of the present disclosure;

FIGS. 39A-39G illustrate elevational and cross-sectional views of thegrowing rod of FIG. 38; and

FIGS. 40A-40B illustrate an exploded view and a magnified exploded viewof components of the growing rod of FIG. 38.

DETAILED DESCRIPTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right”, “left”, “lower” and “upper”designate directions in the drawings to which reference is made. Thewords “inwardly” or “distally” and “outwardly” or “proximally” refer todirections toward and away from, respectively, the patient's body, orthe geometric center of the several implementations of the non-fusionscoliosis expandable spinal rod and related parts thereof. The words,“anterior”, “posterior”, “superior,” “inferior”, “lateral” and relatedwords and/or phrases designate preferred positions, directions and/ororientations in the human body to which reference is made and are notmeant to be limiting. The terminology includes the above-listed words,derivatives thereof and words of similar import.

Referring to FIGS. 1-6, a growing rod 10 in accordance with a firstimplementation of the present disclosure includes a base rod 1, a bottomhousing 2 sealed and preferably laser welded to the base rod 1, a gearhousing 12 preferably laser welded and sealed to the bottom housing 2, atop housing 32 sealed and preferably laser welded to the gear housing 12and a rod 26 that extends out of the top housing 32 and is slidablerelative thereto. The base rod 1 preferably includes a longitudinal slotla therein that receives a torque pin 34 mounted to the rod 26 to limitrotational or pivotal movement of the rod 26 relative to the base rod 1.Accordingly, when the base rod 1 is actuated, as will be described ingreater detail below, the rod 26 generally translates relative to alongitudinal axis of the growing rod 10 and generally does not pivot orrotate except for the play within the tolerances of the constructs. Forde-rotation of the scoliosis, it is also possible to make thelongitudinal slot rotating along the axis of the construct to twist thetwo rods 16/26 against each other.

A magnet 18 is rotatably mounted along the longitudinal axis generallyinside the bottom housing 2 and is preferably enclosed by a bottommagnet cover 20 and a top magnet cover 22. The top and bottom magnetcovers 20, 22 are preferably laser welded together to seal the magnet 18therein and are secured to the magnet 18 for rotation therewith alongthe longitudinal axis. The magnet 18 is preferably diametricallymagnetized including at least two polls 18 a, 18 b and may includemultiple pairs of polls (FIG. 6). The bottom magnet cover 20 includes aneccentric end 20 a spaced from an attachment end 1 b of the base rod 1.

The base rod 1 and the rod 26 include attachment ends 1 b, 26 b that areutilized to attach the growing rod 10 to attachment points or mechanismsA₁-A₈ (FIG. 1A), such as a pedicle screw A₁-A₆, a hook, a cradle A₇-A₈or other attachment mechanisms that permits the surgeon to mount thegrowing rod 10 to the patient's body. The attachment points ormechanisms A₁-A₈ are preferably mounted to bony structures of thepatient's anatomy, such as vertebra V, ribs R, the sacrum S, long bonesor other relatively strong, stiff structures of the patient's anatomy

A gear reduction mechanism that drives the rod 26 to translate relativeto the base rod 1 when the magnet 18 is actuated to rotate is generallypositioned within the gear housing 12. The gear reduction mechanism ofthe first implementation includes a carrier gear 4, a fork 6, a fork pin8 pivotally mounting the fork 6 to the gear housing 12, a ratchet arm 14that is pivotal within the gear housing 12 about the fork pin 8 and apawl 24 that is mounted within the ratchet arm 14. The carrier gear 4includes external gear teeth 4 a that interact with pawl teeth 24 a ofthe pawl 24 and internal gear teeth 4 b that interact with the threads26 a on the rod 26.

A majority of the components of the growing rod 10 of the firstimplementation, with the exception of the magnet 18 are constructed of atitanium or titanium alloy material. However, the components of thegrowing rod 10 are not limited to constructions utilizing titanium ortitanium alloy material and may be constructed of a cobalt-chromiummaterial, a polymeric material or nearly any material that is preferablynon-magnetizable, is generally stiff and strong, is biocompatible, isable to take on the general size and shape of the respective componentsand is able to withstand the normal operating conditions of the growingrod. The magnet 18 is preferably constructed of a permanent magnet or amagnetized material that is able to hold the magnetization during normaloperating conditions. The components and magnet of the remaining severalimplementations, which will be described in greater detail below, arealso preferably constructed of similar materials, unless otherwiseindicated.

In use, in the first implementation, the assembled growing rod 10 ispositioned in a patient's body through a surgical incision. A surgeonmounts attachment points A₁-A₈ to the patient's body at positions thatthe surgeon intends to extend away from each other, such as vertebra Vin a scoliotic spine, the sacrum S, ribs R or other relatively solid,boney structure that is appropriate for fixation. Once the attachmentpositions and mechanisms A₁-A₈ are selected, mounted and contoured tothe patient's body/anatomy, the attachment mechanisms A₁-A₈ are engagedwith the attachment ends 1 b, 26 b of the base rod 1 and rod 26,respectively. The incision is subsequently closed. Over a period oftime, a magnetic field is passed over, via translation or rotationoutside of the patient's body, in proximity to the growing rod 10,thereby causing the magnet 18 to rotate about the longitudinal axis.Rotation of the magnet 18 around the longitudinal axis causes the rod 26to extend away from the base rod 1 and the attachments A₁-A₈ to thepatient's anatomy to extend away from each other. The movement of thegrowing rod 10 for each application of the external magnet or magneticfield to the magnet 18 is preferably small such that the patient'sanatomy is able to adapt to the gradual movement. Specifically, thepatient's soft tissue and boney structure generally are able to adapt tothe small movements to correct the anatomy. The extensions of thegrowing rod 10 are preferably applied over a period of months or yearsand preferably eliminate the need to invasively create an incisionfollowing an initial surgery to extend the growing rod 10, as thegrowing rod 10 of the first implementation is able to extend by applyingthe external magnet or magnetic field.

In use, each translational pass of an external magnet 36 proximate tothe growing rod 10 or each application of an external magnetic fieldcauses the magnet 18 to rotate about the longitudinal axis approximatelyone hundred eighty degrees (180°) (depending on they play in betweenmating parts, could vary ±40°). The growing rod 10 is not limited tobeing actuated by translational movement of the external magnet 36 andmay be actuated by rotation of the external magnet 36 proximate to thegrowing rod 10 or by otherwise applying an external magnetic field tothe growing rod 10.

When the magnet 18 of the growing rod 10 of the first implementation isactuated to rotate, the top and bottom magnet covers 22, 20 rotate withthe magnet 18 about the longitudinal axis. The eccentric end 20 a of thebottom magnet cover 20 is engaged with the fork 6 and causes the fork 6to pivot about the fork pin 8. Pivoting of the fork 6 about the fork pin8 drives an arcuate translation or pivoting movement of a tappet 30,which is fixed to an end of the fork 6 opposite the eccentric end 20 awithin the gear housing 12. The generally up and down arcuatetranslational movement of the tappet 30 drives a pivoting movement ofthe ratchet arm 14 about the fork pin 8. This pivoting movement isdriven by engagement of the tappet 30 in an oblong hole 14 a of theratchet arm 14, within which the tappet 30 slides. This pivotingmovement of the ratchet arm 14 drives the pawl 24 to pivot the carriergear 4 about the longitudinal axis or the pawl 4 or to slip relative tothe carrier gear 4 wherein the pawl teeth 24 a jump over the externalteeth 4 a of the carrier gear 4. That is, the carrier gear 4 isrotatable in only one direction depending upon which pawl groove 24 b alocking ball 16 is positioned. The locking ball 16 is urged into theselected pawl groove 24 b by a biasing spring 28, which allows the pawl24 to slip relative to the carrier gear 4 when attempting to urge thecarrier gear 4 in a rotation direction that the carrier gear 4 is lockedagainst rotating in. Accordingly, for every rotation of the magnet 18,the pawl 24 only urges the carrier gear 4 to rotate in any single onehundred eighty degree (180°) portion of the rotation and slips relativeto the carrier gear 4 during the remainder of the one hundred eightydegree (180°) portion of the rotation. When the pawl 24 is urging thecarrier gear 4 in the non-blocked rotation direction, the internal gearteeth 4 b of the carrier gear 4 engage the threads 26 a on the rod 26 tocause the rod 26 to translate relative to the base rod 1. Preferably,the rod 26 translates away from the base rod 1, but is not so limited.Specifically, the pawl 24 may be arranged such that the locking ball 16is positioned in a pawl groove 24 b that causes the pawl 24 to engageand drive the carrier gear 4 in a reversed direction. If the growing rod10 is arranged to reverse, the actuation of the magnet 18 results in therod 26 translating toward the base rod 1 when the magnet 18 is actuatedor to reduce in length when actuated by the external magnet 36.

Referring to FIGS. 7-9, in a second implementation, the growing rod 210operates in a similar manner to the above-described first implementationof the growing rod 10. Similar reference numerals are utilized toidentify similar components of the second implementation and a prefix“2” is utilized to identify the specific components of the secondimplementation. Differences of the second implementation of the growingrod 210 are described below in comparison to the first implementation.

In the second implementation, the rod 226 is integrally formed with thetop housing 232 and is fixed relative to the bottom housing 202 and thegear housing 212. In addition, the carrier gear 204 includes alongitudinally extending shaft 203 with external threads as opposed tothe internal gear teeth 4 b described in the first implementation of thegrowing rod 10. In addition, the growing rod 210 of the secondimplementation includes a top lid 242 with a slot 242 a extendinglongitudinally along the longitudinal axis. The top lid 242 ispreferably laser welded to the bottom housing 202 and the base rod 201is slidably mounted within the top lid 242 along the longitudinal axis.Torque pins 234 are secured to the base rod 201 that engage the slot 242a of the top lid 242 to urge the base rod 201 to translate along thelongitudinal axis without rotating relative thereto. The base rod 201includes internal threads that engage the external threads of the shaft203 of the carrier gear 204. Accordingly, when the pawl 224 drivesrotation of the carrier gear 204, the external threads on the shaft 203engage and drive the translational movement of the base rod 201 out ofthe top lid 242.

The growing rod 210 of the second implementation also includes a thirdattachment 240 extending from the gear housing 212. The thirdattaclunent 240 is generally offset and substantially parallel to thelongitudinal axis and is utilized as an alternative attaclunent formounting to attaclunent mechanisms A₁-A₈that are attached to thepatient's anatomy. The third attachment 240 is preferably utilized withattachment mechanisms A₁-A₈ that are attached to the patient's anatomyoffset from a longitudinal axis of the growing rod 210 and is preferablyutilized when the attaclunent end 226 b of the rod 226 is not utilized.In use, it is preferred that the attaclunent end 226 b of the rod 226 orthe third attaclunent 240 that is not utilized is cut off of the growingrod 240.

In use, the growing rod 210 of the second implementation is utilized ina similar manner to the growing rod 10 of the first implementation.However, upon actuation of the magnet 218, when the pawl 224 engages anddrives rotation of the carrier gear 204 about the longitudinal axis, thethreaded shaft 203 engages and drives internal gears within the base rod201. This driving of the base rod 201 urges the base rod 201 out of thetop lid 242 such that the attachment end 201 b of the base rod 201extends away from the attachment 226 b of the rod 226 to gradually movethe associated attaclunent points or mechanisms A₁-A₈ in the patient'sanatomy. Sealing of the base rod 201 relative to the top lid 224 occursbetween an internal diameter of the top lid 224 and a generally smooth,circular surface of the base rod 201. Accordingly, such sealing may beadvantageous as the surface of the base rod 201 is generally circular,smooth and continuous nearly from end to end. In contrast, the rod 26 ofthe first implementation includes external threads that will eventuallyextend out of the top housing and may create difficulty for sealingpurposes.

Referring to FIGS. 10-12, in a third implementation, a growing rod 310operates in a similar manner to the above-described first and secondimplementation of the growing rod 10, 210. The similar referencenumerals are utilized to identify similar components of the thirdimplementation and a prefix “3” is utilized to identify the specificcomponents of the third implementation. Differences of the thirdimplementation of the growing rod 310 are described below in comparisonto the first and second implementation. In the third implementation, themagnet 318 and top and bottom magnet covers 320, 322 are offset along amagnet axis that is generally parallel to the longitudinal axis of thegrowing rod 310. The magnet 318 and top and bottom magnet covers 322,320 are housed within the gear housing 312 and the tappet 330 is mountedto the bottom magnet cover 320 to directly drive the ratchet arm 314.Accordingly, in the third implementation, the forks 6, 206 of the firstand second implementations are eliminated from the assembly.

In operation, actuation of the magnet 318 by an external magnetic fieldcauses the magnet 318 and associated top and bottom magnet covers 322,320 to rotate about the offset magnet axis. This rotation causes thetappet 330 on the end of the bottom magnet cover 320 to actuate thepivoting movement of the ratchet arm 314 via engagement of the tappet330 in the oblong hold 314 a of the ratchet arm 314. This rotationsubsequently causes the base rod 301 to move away from the rod 326 as aresult of rotation of the shaft 303.

Referring to FIGS. 13-15, in a fourth implementation, a growing rod 410is substantially similar and includes similar components to theabove-described implementations of the growing rods 10, 210, 310 of thefirst, second and third implementations. The details of each of thecomponents of the fourth implementation of the growing rod 410 are notdescribed herein in detail but only the components that are differentthan the above-described components of the first, second and thirdimplementations are detailed. Similar reference numerals are utilized toidentify the same or similar components and a prefix “4” is utilized tospecifically identify components and elements of the fourthimplementation of the growing rod 410.

The growing rod of 410 of the fourth implementation is similar to thegrowing rod 310 of the third implementation with the exception that therod 426 is translatable along the longitudinal axis with respect to thebase rod 401, which is fixed to first and second components 402 a, 402 bof the bottom housing 402. In use, the growing rod 410 of the fourthimplementation operates in a manner that would be apparent to one havingordinary skill in the art based upon the description of the first andthird implementations of the growing rod 10, 310 and a review ofattached FIGS. 13-15 showing the components of the growing rod 410 ofthe fourth implementation.

Referring to FIGS. 16-18, in a fifth implementation, a growing rod 510operates and has substantially similar components to the above-describedfirst through fourth implementations of the growing rod 10, 210, 310,410. Like reference numerals are utilized to identify like components ofthe growing rod 510 of the fifth implementation with a prefix “5”utilized to specifically identify the components of the fifthimplementation. Components of the growing rod 510 of the fifthimplementation that are different than the above-described components ofthe other implementations are described below and similar or likecomponents are excluded from the detailed description.

In the fifth implementation, the torque pins 534 are mounted to the tophousing 532 proximate to a location where the rod 526 exits the tophousing 534. The rod 526 includes flats 544 extending generallylongitudinally along an external surface that interact with the torquepins 534 to generally prevent or limit pivoting or rotational movementof the rod 526 during operation. In addition, the shaft 503 of thecarrier gear 504 is relatively long and includes the internal teeth 504b generally along an entire internal surface that engage threads 526 athat are substantially located an end of the rod 526 opposite theattachment end 526 b of the rod 526. Accordingly, when the rod 526 isextended from the top housing 532 and the attachment ends 526 b, 501 bof the rod 526 and base rod 1 are secured to the attachment mechanismsA₁-A₈ to correct the patient's anatomy, the base rod 501 b and the rod526 b are generally placed under compression. In the fifthimplementation, the shaft 503 is placed in tension when the rod 526 isplaced in compression.

In use, the growing rod 510 of the fifth implementation operates in asubstantially similar manner to the above-described preferred growingrods 10, 210, 310, 410 and its overall operation will not be described.However, in operation, the shaft 503 of the carrier gear 504 istypically placed in tension when positioned in the anatomy, which may bepreferable for the shaft 503 to react tension load as opposed to acompression load. In addition, the torque pins 534 slide along the flats544 on the rod 526 to limit rotation of the rod 526 when the growing rod510 is in operation. Limiting or generally preventing rotation orpivoting of the rod 526 in operation permits the attachment mechanismsA₁-A₈ that are attached to the patient's anatomy to be fixed to the rod526, thereby eliminating the need for a specific, potentiallycomplicated grasping mechanism that is able to grasp the rod 526 andhold the rod as it rotates during use. However, the rod 526 and the baserod 501 are not limited to being free from rotation during use and maybe mounted to the attachment mechanisms A₁-A₈ utilizing adaptors thatpermit rotation of the rod 526 and the base rod 501 and secureengagement with the attachment mechanisms A₁-A₈. For example, one of theattachment mechanisms A₁-A₈ may be comprised of a pedicle screw (notshown) with a bearing or bushing therein that permits rotation of therod 526 or base rod 501 attached thereto while securing the rod 526 andbase rod 501 to the pedicle screw such that the pedicle screw translatesas the rod 526 or base rod 501 translates.

Referring to FIGS. 19-23, in a sixth implementation, a growing rod 610has similar components and operates in a similar manner to theabove-described implementations of the growing rods 10, 210, 310, 410,and 510. Like reference numerals are utilized to identify likecomponents and a prefix “6” is utilized to specifically identify thecomponents and elements of the growing rod 610 of the sixthimplementation.

Components of the growing rod 610 of the sixth implementation that aredifferent than the components of the above-described first through fifthimplementations of the growing rod 10, 210, 310, 410, 510 are describedbelow while repeat description of the similar or same components areomitted.

The growing rod of the sixth implementation integrally forms the gearhousing 612, bottom housing 602 and base rod 601 in a single, integralcomponent. Accordingly, the external housing components of the sixthimplementation of the growing rod 610 are generally limited to theintegral base rod 601, bottom housing 602 and gear housing 612, which ispreferably laser welded to the top housing 632. The rod 626 is the onlyother component visible on the outside to the completely assembledgrowing rod 610 and extension of the rod 626 out of the top housing 632is the only seal besides the laser-welding of the top housing 632 to thegear housing 612 that is sealed to .the patient's anatomy or to otheroutside influences. Accordingly, the growing rod 610 of the sixthimplementation has a relatively lowered part count and simplifiedsealing requirement when compared to the previously describedimplementations.

Referring specifically to FIGS. 21-22, operation of the pawl 624 todrive the carrier gear 604 in forward and reverse directions is shown incross-section. Specifically, the locking ball 616 is positioned in afirst of the pawl grooves 624 b when the growing rod 610 is operating inthe forward direction and the locking ball 616 is positioned in theother of the pawl grooves 624 b when the growing rod 610 is operating inthe reverse direction. This manipulation of the position of the lockingball 616 in one of the pawl grooves 624 b blocks rotation of the carriergear 604 in one direction and drives rotation of the carrier gear 604 inthe opposite direction. Such a manipulation of the pawl 624 of the sixthimplementation is identical to the manner in which the otherimplementations of the growing rods 10, 210, 310, 410, 510 may bemanipulated to operate in forward and reverse directions. Accordingly,if a surgeon desires to draw the attachment ends 601 b, 626 b of thebase rod 601 and the rod 626 toward each other, the growing rod 610 andany of the other preferred growing rods 10, 210, 310, 410, 510 may beconfigured in this manner. Accordingly, the preferred growing rods 10,210, 310, 410, 510, 610 are able to grow or contract depending upon howthe surgeon prefers to utilize the rods 10, 210, 310, 410, 510, 610. Forexample, referring to FIG. 1A, the growing rod 10 on the right lateralside of the scoliotic spine are preferably configured to contract todraw the ribs R on the open side of the scoliotic “C” curve together,while the growing rods 1° on the left lateral side of the scolioticspine are preferably configured to expand to urge the ribs R and/orvertebra V on the closed side of the scoliotic “C” curve apart in anattempt to realign or move the spine toward a more anatomically correctcurvature. In addition, the growing rod 1° mounted to the sacrum S andthe lumbar vertebrae V may also be configured to contract to correctscoliotic curve of the lumbar section of the spine.

Referring to FIGS. 25-27 in a seventh implementation, a growing rod 50is comprised of a spur gear-type mechanism. The growing rod 50 of theseventh implementation includes a top housing 52 with an attachment end52 a, a gear housing 54 preferably laser welded to the top housing 52, abottom housing 56 preferably laser welded to the gear housing 54 and arod 56 including an attachment end 58 a that movably extends out of thebottom housing 56 along a longitudinal axis. The attachment ends 52 a,58 a of the top housing 52 and rod 58, respectively, are utilized toattach the growing rod 50 to the attachment mechanisms A₁-A₈ that arefixed to boney structures of the patient's anatomy. The indications forthe growing rod 50 of the seventh implementation are similar to theindications and manner of attaching the growing rods 10, 210, 310, 410,510, 610 of the above-described implementations and are not described infurther details with respect to the growing rod 50 of the seventhimplementation.

The growing rod 50 of the seventh implementation also includes a magnet64 having poles that is utilized to drive the operation of the growingrod 50 with an external magnet or magnetic field to permit the growingrod 50 to move without invasive surgical techniques. The magnet 64 ismounted within a top magnet cover 60 and a bottom magnet cover 62. Themagnet 64, top magnet cover 60 and bottom magnet cover 62 are generallymounted within the top housing 52 along the longitudinal axis and arepivotal about the longitudinal axis. The top magnet cover 60 includes apivot pin 60 a that is secured in a bearing or bushing 74 within the tophousing 52 and the bottom magnet cover 62 includes a pivot pin 62 aextending away from the magnet 64.

The magnet 64 drives translation of the rod 58 via a gear reductionmechanism. The gear reduction mechanism includes a small central gear 66mounted on the pivot pin 62 a of the bottom magnet cover 62, a pair ofrelatively large offset gears 68, a pair of spindles 70 that are securedto the large offset gears 68 and a carrier 72 that is threadably securedto the spindles 70 and is fixed to an end of the rod 58. The rod 58 isisolated from rotation relative to the gear housing 54 by mounting therod 58 to the carrier 72, which slides within a slot in the gear housing54 and bottom housing 56.

In use, the growing rod 50 is mounted at the attachment ends 52 a, 58 ato attachment mechanisms A₁-A₈ that are secured to the patient and thesurgical incision is closed. A surgeon, medical professional or othercaregiver may extend or retract the rod 50 without additional incisionsby passing a magnet proximate to the growing rod 50 or by applying amagnetic field to the growing rod 50 to cause the magnet 64 to rotatewithin the top housing 52. Rotation of the magnet 64 drives rotation ofthe small central gear 66, which also drives rotation of the largeoffset gears 68. Rotation of the large offset gears 68 causes thespindles 70 to rotate and urge the carrier 72 along the longitudinalaxis, preferably toward a distal end of the bottom housing 56 whenoperating in a forward or expanding direction. As the carrier 72translates along the longitudinal axis, the rod 52 is urged out of thebottom housing 56 and the distance between the fasteners or attachmentmechanisms A₁-A₈ secured to the attachment ends 52 a, 58 a are drivenapart. Consequently, the patient's anatomy is gradually shifted to urgethe anatomy toward an anatomically correct orientation.

Similar to the above-described preferred growing rods 10, 210, 310, 410,510, 610, the growing rod 50 and its components are preferablyconstructed of titanium or titanium alloys but are not so limited andmay be constructed of cobalt chromium material, polymeric materials ornearly any bio-compatible material that is relatively strong and stiff,is able to take on the general size of the growing rod 50 and itscomponents and able to withstand normal operating conditions of thegrowing rod 50. However, the bearings 74 are preferably constructed of aPolyether ether ketone (PEEK) material that is biocompatible and has arelatively low coefficient friction. The bearings 74 are not limited toconstructions utilizing PEEK materials and may be constructed of nearlyany material that permits the associated parts to slide relative theretofor pivoting.

Referring to FIGS. 28-31, in an eighth implementation, a growing rod 80is comprised of an excenter-style growing rod 80. The externalcomponents of the growing rod 80 of the eighth implementation include atop housing 82 with an attachment end 82 a, a gear housing 84 preferablylaser welded to the top housing 82, a middle housing 86 preferably laserwelded to the gear housing 84, a bottom housing 88 preferably laserwelded to the middle housing 86 and a rod 90 that movably extends out ofthe bottom housing 88. The rod 90 includes an attachment end 90 a thatalong with the attachment end 82 a of the top housing 82 are used tosecure the growing rod 80 to attachment mechanisms A₁-A₈ and thepatient's anatomy. The growing rod 80 also includes a magnet 96 that ispolarized and rotates when actuated by passing a magnet in closeproximity thereto or a magnetic field. The magnet 96 is secured betweena magnet bottom cover 95 and a magnet top cover 97, preferably withinthe middle housing 86.

The movement of the rod 90 is driven by the magnet 96 through a gearreduction mechanism of the eighth implementation of the growing rod 80.The gear reduction mechanism includes an eccentric end 95 a on an end ofthe magnet bottom cover 95, a gear wheel 94 secured to the eccentric end95 a that includes eccentric holes 94 a and mates with internal teeth 84a of the gear housing 84, driver pins 92 that loosely fit in theeccentric holes 94 a of the gear wheel 94 and a driver wheel 91 to whichthe driver pins 92 are fix. The driver wheel 91 includes a threadedshaft 91 a that mates with internal threads of the rod 90. A slider 98is fixed to the bottom housing 88 and includes a pair of slots 98 atherein that receive torque pins 93 fixed to the rod 90 to prevent orlimit any pivotal or rotational movement of the rod 90 during operationof the growing rod 80. A carrier 78 having internal threads is mountedto the threaded shaft 91 a of the driver wheel 91 and is secured to thetorque pins 93 to urge the rod 90 out of the bottom housing 88.

In operation, the growing rod 80 is mounted to the attachment mechanismsA₁-A₈ within the patient and the magnet 96 is actuated to rotate.Rotation of the magnet 96 causes the magnet bottom cover 95 and the gearwheel 94 to rotate. The gear teeth on the external surface of the gearwheel 94 are mismatched with the internal gear teeth 84 a of the gearhousing 84 such that the eccentric rotation of the gear wheel 94 causesthe gear teeth to mesh, but the internal bearing 99 a permits the gearwheel 94 to rotate approximately one fifteenth ( 1/15) of a fullrotation for every full rotation of the magnet 96. This reduced rotationof the gear wheel 94 is transmitted to the driver wheel 91 through thedriver pins 92. Rotation of the driver wheel 91 causes rotation of thethreaded shaft 91 a and translational movement of the carrier 78 and rod90 relative to the threaded shaft: 91 a. Engagement between the torquepins 93 and the slots 98 a in the slider 98 permit the rod 90 totranslate out of the bottom housing 88 to expand the growing rod 80.

Referring to FIGS. 32-34, in a ninth implementation, a growing rod 950is substantially similar to and includes similar components to thegrowing rod 50 of the seventh implementation. Like reference numeralsare utilized to identify like elements of the ninth implementation incomparison to the seventh implementation with a prefix “9” tospecifically identify the components of the growing rod 950 of the ninthimplementation. Detailed descriptions of each of the components of thegrowing rod 950 of the ninth implementation are omitted and differencesbetween the growing rod 950 of the ninth implementation and the growingrod 50 of the seventh implementation are highlighted in the belowdescription.

In the ninth implementation, the gear housing 954 of the growing rod 950houses a majority of the magnet 964, bottom magnet cover 962 and topmagnet cover 960. Accordingly, the length of the growing rod 950 inaccordance with the ninth implementation having the spur gear-style isshortened in comparison to the spur gear-style growing rod 50 of theseventh implementation because the magnet 964, spindles 970 and rod 958are concentrated in one section in parallel along the longitudinal axisof the growing rod 950 within the gear housing 954, as opposed to theseventh implementation of the growing rod 50 wherein the magnet 64 andspindles 70 are independently positioned in series along thelongitudinal axis.

A maximum width of the gear housing 954 of the ninth implementation mayalso be slightly reduced in comparison to the gear housing 54 of thegrowing 50 of the seventh implementation because of an offset of thesmall central gear 966 relative to the longitudinal axis and the largeoffset gears 968. In contrast, the small central gear 66 of the growingrod 50 of the seventh implementation is generally coaxially located onthe longitudinal axis, thereby requiring a slightly larger maximum widthfor the gear housing 54 to accommodate the positioning of the centralgear 66 and the offset gears 68.

Referring to FIGS. 35-37, in a tenth implementation, a growing rod 1080has an excenter-style design similar to the growing rod 80 of the eighthimplementation. Like reference numerals are utilized to identify likecomponents of the growing rod 1080 of the tenth implementation with aprefixed “10” utilized to identify the specific components of the tenthimplementation in comparison to the growing rod 80 of the eighthimplementation. The growing rod 1080 of the tenth implementation issubstantially similar to the growing rod 80 of the eighth implementationand only components of the growing rod 1080 of the tenth implementationthat are different than those of the eighth implementation are describedbelow.

The gear housing 1084 of the tenth implementation is utilized as anintegral component to comprise the separate gear housing 84 and middlehousing 86 of the eighth implementation. Accordingly, the gear housing1084 of the tenth implementation reduces part count and the number ofseals required during the manufacturing process. The carrier 1078 of thegrowing rod 1080 of the tenth implementation is a keyed-design that isslidable within an internal surface of an internal extension 1088 a ofthe bottom housing 1088. This configuration eliminates the slider 98 aswell as the separate torque pins 93 described in the growing rod 80 ofthe eighth implementation.

Referring to FIGS. 38-40, in an eleventh implementation, a growing rod1150 is substantially similar to the growing rod 950 of the ninthimplementation. Like reference numerals are utilized to identify likeelements and components that are different than the components of thegrowing rod 950 of the ninth implementation are highlighted below.

The growing rod 1150 of the eleventh implementation is constructed suchthat the magnet 1164 and a single spindle 1170 are positioned within thegear housing 1154 at a similar position in parallel along thelongitudinal axis. In addition, the growing rod 1150 of the eleventhimplementation includes a gear-reduction mechanism 1100 having fourgears that reduce the rotational output of the spindle 1170 relative toan input rotation of the magnet 1164. The growing rod 1150 of theeleventh implementation further includes a carrier 1172 that is keyed toslide within the gear housing 1154 to prevent or limit pivoting orrotation of the rod 1158 during use. The carrier 1172 is keyed in asimilar manner to the carrier 1078 of the growing rod 1080 of the tenthimplementation.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisdisclosure is not limited to the particular embodiments disclosed, butit is intended to cover modifications within the spirit and scope of thepresent disclosure as defined by the present description.

What is claimed:
 1. A growing rod, comprising: a base rod having anattachment end; an extendable rod being translatable relative to thebase rod along a longitudinal axis; a housing enclosing at least aportion of the extendable rod therein; a magnet rotatably mounted withinthe housing and enclosed by a top magnet cover and a bottom magnetcover, the magnet including a first pole and a second pole; and a gearreduction mechanism associated with the magnet and the extendable rod,the gear reduction mechanism reducing an output rotation to theextendable rod in comparison to an input rotation from the magnet. 2.The growing rod of claim 1, wherein the extendable rod moves along thelongitudinal axis substantially without rotation relative to the baserod.
 3. The growing rod of claim 1, wherein the base rod and theextendable rod each include an attachment end that are attached toattachment points within a patient's body.
 4. The growing rod of claim3, wherein the attachment points are one of a pedicle screw, a hook anda cradle.
 5. The growing rod of claim 1, wherein the gear reductionmechanism further comprises: a carrier gear having external gear teethand internal gear teeth; a fork; a fork pin pivotally mounting the forkto a gear housing; a ratchet arm that is pivotal within the gear housingabout the fork pin; and a pawl that is mounted within the ratchet arm,wherein the internal gear teeth mesh with threads on the extendable rodto cause the extendable rod to move relative to the base rod along thelongitudinal axis.
 6. The growing rod of claim 5, wherein rotation ofthe magnet by a magnetic field causes the ratchet arm to drive the pawlthat pivots the carrier gear about the longitudinal axis by aninteraction of pawl teeth and the external threads.
 7. The growing rodof claim 5, further comprising a locking mechanism that engages thepawl, wherein a position of the locking mechanism within the pawl blocksa rotational direction of the carrier gear.
 8. The growing rod of claim7, wherein an unblocked rotational direction causes the extendable rodto translate in a direction away from the base rod along thelongitudinal direction.
 9. The growing rod of claim 7, wherein anunblocked rotational direction causes the extendable rod to translate ina direction toward the base rod along the longitudinal direction. 10.The growing rod of claim 1, wherein the growing rod, with an exceptionof the magnet, is constructed of a non-magnetizable material.
 11. Thegrowing rod of claim 10, wherein the non-magnetizable material compriseone of titanium, a titanium alloy material, a cobalt-chromium materialand a polymeric material.
 12. The growing rod of claim 1, wherein theextendable rod is moved relative to the base rod along the longitudinalaxis by passing a magnetic field in proximity to the growing rod tocause the magnet to rotate about the longitudinal axis.
 13. The growingrod of claim 1, wherein the gear reduction mechanism further comprises:a gear housing having internal gear teeth; a gear wheel having externalgear teeth; a driver wheel having diver pins fixed thereto and that arefitted within the gear wheel, the driver wheel including a threadedshaft; and a carrier that mates with the threaded shaft and mates withextendable rod by torque pins.
 14. The growing rod of claim 13, whereinthe external gear teeth are mismatched with the internal gear teeth suchthat the rotation of the gear wheel causes the external gear teeth andthe internal gear teeth to mesh, and wherein the gear wheel rotates lessthan a full rotation for each full rotation of the magnet.
 15. Thegrowing rod of claim 14, wherein the gear wheel rotates approximatelyone-fifteenth of a rotation for each full rotation of the magnet. 16.The growing rod of claim 13, wherein rotation of gear wheel istransmitted to the driver wheel through the driver pins, and whereinrotation of the driver wheel causes rotation of the threaded shaft andthe carrier to move the extendable rod out of the housing.
 17. Thegrowing rod of claim 13, further comprising a slider that is fixed tohousing, the slider including a pair of slots that receive the torquepins to limit rotational movement of the extendable rod.
 18. The growingrod of claim 1, wherein the gear reduction mechanism further comprises:a gear housing having internal gear teeth; a gear wheel having externalgear teeth; a driver wheel having diver pins fixed thereto that arefitted within the gear wheel, the driver wheel including a threadedshaft; and a carrier that mates with the threaded shaft and toextendable rod by a keyway.
 19. The growing rod of claim 18, whereinrotation of gear wheel is transmitted to the driver wheel through thedriver pins, and wherein rotation of the driver wheel causes rotation ofthe threaded shaft and the carrier to move the extendable rod out of thehousing.
 20. The growing rod of claim 18, wherein the interaction of thecarrier and the extendable rod through the keyway limits rotationalmovement of the extendable rod.
 21. A growing rod, comprising: ahousing; a fixed rod that is attached to the housing at a first end ofthe housing; an extendable rod that moves along a longitudinal axis ofthe growing rod and extending from a second end of the housing; a magnetmounted within the housing; and a gear reduction mechanism, whereinmovement of the magnet caused by an external magnetic field is input tothe gear reduction mechanism, and wherein the gear reduction mechanismreduces the input movement to produce an output that is translated intolongitudinal movement of the extendable rod.
 22. The growing rod ofclaim 21, wherein the magnet includes at least two polls, and whereinthe extendable rod is moved relative to the fixed rod along thelongitudinal axis by passing a magnetic field in proximity to thegrowing rod to cause the magnet to rotate about the longitudinal axis.23. The growing rod of claim 21, wherein the gear reduction mechanismfurther comprises: a gear housing; a carrier gear driven by a ratchetarm that is pivotally mounted within the gear housing; and a pawl thatis mounted within the ratchet arm, wherein movement of the ratchet armdrives the pawl to engage pawl teeth with external gear teeth of thecarrier gear, and wherein internal gear teeth of the carrier gear meshwith threads on the extendable rod to cause the extendable rod totranslatable relative to the fixed rod along the longitudinal axis. 24.The growing rod of claim 23, further comprising a locking mechanism thatengages the pawl, wherein a position of the locking mechanism within thepawl blocks a first rotational direction of the carrier gear and allowsa second rotational direction of the carrier gear.
 25. The growing rodof claim 24, wherein the first rotational direction causes theextendable rod to translate in a direction away from the fixed rod alongthe longitudinal direction.
 26. The growing rod of claim 23, wherein ansecond rotational direction causes the extendable rod to translate in adirection toward the fixed rod along the longitudinal direction.
 27. Thegrowing rod of claim 23, wherein the gear reduction mechanism further,comprises a gear housing having internal gear teeth; a gear wheel havingexternal gear teeth; a driver wheel having diver pins fixed thereto thatare fitted within the gear wheel, the driver wheel including a threadedshaft; and a carrier that mates with the threaded shaft and toextendable rod by torque pins.
 28. The growing rod of claim 27, whereinthe external gear teeth are mismatched with the internal gear teeth suchthat the gear wheel rotates less than a full rotation for each fullrotation of the magnet.
 29. The growing rod of claim 27, furthercomprising a slider that is fixed to housing, the slider including apair of slots that receive the torque pins to limit rotational movementof the extendable rod.
 30. The growing rod of claim 21, wherein the gearreduction mechanism further comprises: an gear housing having internalgear teeth; a gear wheel having external gear teeth; a driver wheelhaving diver pins fixed thereto that are fitted within the gear wheel,the driver wheel including a threaded shaft; and a carrier that mateswith the threaded shaft and to extendable rod by a keyway.
 31. Thegrowing rod of claim 30, wherein the interaction of the carrier and theextendable rod through the keyway limits rotational movement of theextendable rod.
 32. An expandable spinal growing rod, comprising: afirst rod that is fixedly attached to a housing at a first end of thehousing; a second rod that extends from a second end of the housing andthat moves along a longitudinal axis; and a magnet within the housing;and a gear mechanism that is engaged by the magnet, wherein inputrotational movement of magnet drives the gear mechanism, and whereinrotational movement of the gear mechanism is translated intolongitudinal movement of the second rod relative to the housing.
 33. Thespinal growing rod of claim 32, wherein the second rod moves along thelongitudinal axis substantially without rotation relative to the firstrod.
 34. The spinal growing rod of claim 32, wherein the gear mechanismcomprises a gear reduction mechanism that reduces the input rotationalmovement of magnet with respect to an output of the gear mechanism. 35.The spinal growing rod of claim 32, wherein the gear mechanism rotatesbi-directionally such that second rod is moveable relative to the firstrod along the longitudinal axis in a first direction away from the firstrod or in a second direction toward the first rod.
 36. The spinalgrowing rod of claim 35, further comprising a locking mechanism thatengages within gear mechanism to block rotation of the gear mechanismsuch that the second rod moves in the first direction or the seconddirection in accordance with a position of the locking mechanism. 37.The spinal growing rod of claim 32, wherein the input rotation movementof the gear mechanism is caused by passing a magnetic field in proximityto the magnet of the spinal growing rod.